TRPA1 (Transient Receptor Potential Cation Channel, Subfamily A, member 1) was first found in peripheral sensory nerve fibers in 2003 owing to the studies in the fields of human physiology and pharmacology. TRPA1 is activated by detecting diverse stimuli including cold temperature, inflammatory and mechanical stresses, etc. And human body feels pain by the activation. TRPA1 belongs to thermoTRP family (temperature-sensitive transient receptor potential ion channels) that is the pain receptor family recognizing temperature and painful stimuli. Many researchers expect that human pain mechanism will be disclosed by understanding the functions of TRPA1, the pain receptor, and finally the goal of relieving pain will be achieved by the development of a TRPA1 regulator.
Studies have been actively undergoing to relieve pain, but the mechanism of hangover pain caused by heavy ethanol intake or drinking has not been explained, yet. It is most likely that hangover pain is induced by acetaldehyde and prostaglandin. The conventional hangover pain relievers developed so far are all to reduce the in vivo concentration of acetaldehyde or prostaglandin, the hangover pain inducer, though whose mechanisms are unknown. A screening method of a hangover pain reliever in relation to the activation of TRPA1 has not been established, yet.
To understand basic techniques used for the development of a hangover pain reliever based on the inhibition of TRPA1 activation, it is important to understand the characteristics of TRPA1. TRPA1 is an ion channel and its activation makes cations to migrate into sensory neurons, causing the changes in membrane currents. The changes of membrane currents generate action potential signal and this potential signal is transmitted to the brain where pain is recognized. One of the techniques to measure the TRPA1 activation is patch-clamp electrophysiology technique measuring the changes of membrane currents after amplifying thereof. And another technique to measure the TRPA1 activation is to measure intracellular calcium level based on the fact that TRPA1 is involved in the migration of cations such as calcium ions. The first technique is superior in sensitivity to the second one, but the second technique is superior in high speed to the first one, so that they are complementary to each other. Such techniques to measure the TRPA1 activation can be executed by the support of animal neuron culture technique, cell line culture technique, TRPA1 DNA control and transfection techniques. To screen a TRPA1 inhibitor and to measure its inhibition activity, various TRPA1 specific inhibitor candidates and standard activators are introduced into TRPA1 over-expressing cells and the inhibition effect on the TRPA1 activation thereby was observed.
Therefore, the present inventors constructed transformants expressing TRP and treated them with acetaldehyde, the hangover pain inducer, and other chemicals known as TRP inhibitors, followed by comparison of the results. As a result, the inventors completed this invention by confirming that acetaldehyde activated TRPA1 specifically and thus it can be effectively used for the screening of a hangover pain reliever.